1. Field of the Invention
The present invention relates to a vibration-absorbing handle cover for a hand tool such as a hammer.
2. Description of the Related Art
Hammers generally have a wooden or plastic handle with poor vibration-absorbing capability. When hammering, vibrations occur along a vertical direction of the hammer. The vibrations are greater when the hammered object is more rigid. Thus, the four fingers other than the thumb as well as the area between the thumb and the index finger of the user""s hand are often numb with or even injured by the vertical vibrations generated by the reactive force as a result of hammering. U.S. Pat. No. 6,170,362 to Chen issued on Jan. 9, 2001 discloses a shockproof structure of the handle cover of a hand tool. The handle cover is made of soft, elastic material and comprises an inserting portion for receiving a handle of a hand tool. Vents are provided at sides of upper and lower portions of the handle cover. Each vent has a certain depth within the handle cover without penetrating the handle cover. However, the handle cover could not absorb all of the vibrations generated as result of hammering. At best, the handle cover may absorb a part of the vibrations to an extent that the remaining vibrations transmitted to the user""s hand are harmless to the user. However, two sides of the handle cover could deform in an asymmetric manner when the user holds the handle cover with a large force. Further, the two sides of the handle cover have different softness, as the vents are asymmetrically defined in a side of the handle cover without penetrating the handle cover. Further, no vibration-absorbing function is provided if the user holds the handle cover in a reverse direction. Further, the vents are not uniform in dimensions such that the vents could not deform by the same magnitude. The non-uniform deformation of the handle cover during operation adversely affects the vibration-absorbing function. The user would feel uncomfortable and non-uniform absorption of vibrations occurs, which would lead the user to injury.
U.S. Pat. No. 811,390 to Foreman issued on Jan. 30, 1906 discloses a handle having a plurality of annularly disposed axially extending channels in an outer periphery thereof for absorbing vibrations. However, the shock-absorbing effect is poor. U.S. Pat. No. 4,738,166 to Yamaguchi issued on Apr. 19, 1988 discloses a helve of a hammer comprising upper and lower axially extending passages and a plurality of openings on two sides of the helve. However, the openings are not communicated with the axially extending passages, and the shock-absorbing effect is poor.
U.S. Pat. No. 6,220,128 to Hu issued on Apr. 24, 2001 discloses a shock-absorbing handle of a hand impact tool comprising upper and lower axial passages and several rows of openings communicated with the axial passages. The shock-absorbing effect is improved. However, the hammer tends to slip from the user""s hand during hammering. This is owing to the fact that two ends of each axial passage are communicated with outside. Further, manufacture of this handle requires a complicated, costly mold in which a difficult process of drawing a bar for forming the respective axial passage must be proceeded after injection molding.
An object of the present invention is to provide a vibration-absorbing handle cover for a hand tool. The handle cover is capable of providing a more uniform vibration-absorbing effect during operation. It is achieved by means of removing the material from an upper portion and a lower portion of the handle cover, thereby reducing the amount of material that transmits the vibrations. The shock-absorbing handle cover can be manufactured by simple, inexpensive molds in an easier manner.
In accordance with a first aspect of the invention, a handle cover is made of soft material and includes a central longitudinal compartment for receiving a handle of a tool. A plurality of first holes and a plurality of second holes are defined in an upper portion of the handle cover. The first holes and the second holes are alternately disposed along a longitudinal direction of the handle cover with each first hole extending in a direction transverse to the longitudinal direction of the handle cover and having an opening in a left side of the upper portion of the handle cover and with each second hole extending in the direction transverse to the longitudinal direction of the handle cover and having an opening in a right side of the upper portion of the handle cover. Each first hole is delimited by a first end wall on the right side of the upper portion of the handle cover. Each second hole is delimited by a second end wall on the left side of the upper portion of the handle cover.
A plurality of third holes and a plurality of fourth holes are defined in a lower portion of the handle cover. The third holes and the fourth holes are alternately disposed along the longitudinal direction of the handle cover with each third hole extending in the direction transverse to the longitudinal direction of the handle cover and having an opening in a left side of the lower portion of the handle cover and with each fourth hole extending in the direction transverse to the longitudinal direction of the handle cover and having an opening in a right side of the lower portion of the handle cover. Each third hole is delimited by a third end wall on the right side of the lower portion of the handle cover. Each fourth hole is delimited by a fourth end wall on the left side of the lower portion of the handle cover.
By such an arrangement, the material for transmitting vibrations along the vertical direction is removed to an extent that the remaining vibrations transmitted to the user""s hand is harmless. The holes allow the handle cover to deform during hammering. The user may firmly grasp the handle cover without the risk of slip due to the balanced arrangement of the holes.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.